Anorectal fistulas test the performance and experience of colon and rectal surgeons.This review paper was performed to discuss the most recent advances in the diagnosis and treatment of complex anorectal fistulas.Failures to treatment of anorectal fistulas may be reduced only by fully knowledge of the anorectal anatomy, and all the possible routes that the fistulas could go through. Their complexity is directly related to their relationship with the anal sphincter, which should be considered by the surgeon in order to take care of the perfect identification and localization of their origin. Treatment should be individualized to each patient.The role of the diverse surgical alternatives will depend upon the characteristics and relationships of the fistulous tract and the sphincter.